drivers/media/pci/solo6x10/solo6x10-i2c.c

   1 // SPDX-License-Identifier: GPL-2.0-or-later
   2 /*
   3  * Copyright (C) 2010-2013 Bluecherry, LLC <http://www.bluecherrydvr.com>
   4  *
   5  * Original author:
   6  * Ben Collins <bcollins@ubuntu.com>
   7  *
   8  * Additional work by:
   9  * John Brooks <john.brooks@bluecherry.net>
  10  */
  11
  12 /* XXX: The SOLO6x10 i2c does not have separate interrupts for each i2c
  13  * channel. The bus can only handle one i2c event at a time. The below handles
  14  * this all wrong. We should be using the status registers to see if the bus
  15  * is in use, and have a global lock to check the status register. Also,
  16  * the bulk of the work should be handled out-of-interrupt. The ugly loops
  17  * that occur during interrupt scare me. The ISR should merely signal
  18  * thread context, ACK the interrupt, and move on. -- BenC */
  19
  20 #include <linux/kernel.h>
  21 #include <linux/sched/signal.h>
  22
  23 #include "solo6x10.h"
  24
  25 u8 solo_i2c_readbyte(struct solo_dev *solo_dev, int id, u8 addr, u8 off)
  26 {
  27         struct i2c_msg msgs[2];
  28         u8 data;
  29
  30         msgs[0].flags = 0;
  31         msgs[0].addr = addr;
  32         msgs[0].len = 1;
  33         msgs[0].buf = &off;
  34
  35         msgs[1].flags = I2C_M_RD;
  36         msgs[1].addr = addr;
  37         msgs[1].len = 1;
  38         msgs[1].buf = &data;
  39
  40         i2c_transfer(&solo_dev->i2c_adap[id], msgs, 2);
  41
  42         return data;
  43 }
  44
  45 void solo_i2c_writebyte(struct solo_dev *solo_dev, int id, u8 addr,
  46                         u8 off, u8 data)
  47 {
  48         struct i2c_msg msgs;
  49         u8 buf[2];
  50
  51         buf[0] = off;
  52         buf[1] = data;
  53         msgs.flags = 0;
  54         msgs.addr = addr;
  55         msgs.len = 2;
  56         msgs.buf = buf;
  57
  58         i2c_transfer(&solo_dev->i2c_adap[id], &msgs, 1);
  59 }
  60
  61 static void solo_i2c_flush(struct solo_dev *solo_dev, int wr)
  62 {
  63         u32 ctrl;
  64
  65         ctrl = SOLO_IIC_CH_SET(solo_dev->i2c_id);
  66
  67         if (solo_dev->i2c_state == IIC_STATE_START)
  68                 ctrl |= SOLO_IIC_START;
  69
  70         if (wr) {
  71                 ctrl |= SOLO_IIC_WRITE;
  72         } else {
  73                 ctrl |= SOLO_IIC_READ;
  74                 if (!(solo_dev->i2c_msg->flags & I2C_M_NO_RD_ACK))
  75                         ctrl |= SOLO_IIC_ACK_EN;
  76         }
  77
  78         if (solo_dev->i2c_msg_ptr == solo_dev->i2c_msg->len)
  79                 ctrl |= SOLO_IIC_STOP;
  80
  81         solo_reg_write(solo_dev, SOLO_IIC_CTRL, ctrl);
  82 }
  83
  84 static void solo_i2c_start(struct solo_dev *solo_dev)
  85 {
  86         u32 addr = solo_dev->i2c_msg->addr << 1;
  87
  88         if (solo_dev->i2c_msg->flags & I2C_M_RD)
  89                 addr |= 1;
  90
  91         solo_dev->i2c_state = IIC_STATE_START;
  92         solo_reg_write(solo_dev, SOLO_IIC_TXD, addr);
  93         solo_i2c_flush(solo_dev, 1);
  94 }
  95
  96 static void solo_i2c_stop(struct solo_dev *solo_dev)
  97 {
  98         solo_irq_off(solo_dev, SOLO_IRQ_IIC);
  99         solo_reg_write(solo_dev, SOLO_IIC_CTRL, 0);
 100         solo_dev->i2c_state = IIC_STATE_STOP;
 101         wake_up(&solo_dev->i2c_wait);
 102 }
 103
 104 static int solo_i2c_handle_read(struct solo_dev *solo_dev)
 105 {
 106 prepare_read:
 107         if (solo_dev->i2c_msg_ptr != solo_dev->i2c_msg->len) {
 108                 solo_i2c_flush(solo_dev, 0);
 109                 return 0;
 110         }
 111
 112         solo_dev->i2c_msg_ptr = 0;
 113         solo_dev->i2c_msg++;
 114         solo_dev->i2c_msg_num--;
 115
 116         if (solo_dev->i2c_msg_num == 0) {
 117                 solo_i2c_stop(solo_dev);
 118                 return 0;
 119         }
 120
 121         if (!(solo_dev->i2c_msg->flags & I2C_M_NOSTART)) {
 122                 solo_i2c_start(solo_dev);
 123         } else {
 124                 if (solo_dev->i2c_msg->flags & I2C_M_RD)
 125                         goto prepare_read;
 126                 else
 127                         solo_i2c_stop(solo_dev);
 128         }
 129
 130         return 0;
 131 }
 132
 133 static int solo_i2c_handle_write(struct solo_dev *solo_dev)
 134 {
 135 retry_write:
 136         if (solo_dev->i2c_msg_ptr != solo_dev->i2c_msg->len) {
 137                 solo_reg_write(solo_dev, SOLO_IIC_TXD,
 138                                solo_dev->i2c_msg->buf[solo_dev->i2c_msg_ptr]);
 139                 solo_dev->i2c_msg_ptr++;
 140                 solo_i2c_flush(solo_dev, 1);
 141                 return 0;
 142         }
 143
 144         solo_dev->i2c_msg_ptr = 0;
 145         solo_dev->i2c_msg++;
 146         solo_dev->i2c_msg_num--;
 147
 148         if (solo_dev->i2c_msg_num == 0) {
 149                 solo_i2c_stop(solo_dev);
 150                 return 0;
 151         }
 152
 153         if (!(solo_dev->i2c_msg->flags & I2C_M_NOSTART)) {
 154                 solo_i2c_start(solo_dev);
 155         } else {
 156                 if (solo_dev->i2c_msg->flags & I2C_M_RD)
 157                         solo_i2c_stop(solo_dev);
 158                 else
 159                         goto retry_write;
 160         }
 161
 162         return 0;
 163 }
 164
 165 int solo_i2c_isr(struct solo_dev *solo_dev)
 166 {
 167         u32 status = solo_reg_read(solo_dev, SOLO_IIC_CTRL);
 168         int ret = -EINVAL;
 169
 170
 171         if (CHK_FLAGS(status, SOLO_IIC_STATE_TRNS | SOLO_IIC_STATE_SIG_ERR)
 172             || solo_dev->i2c_id < 0) {
 173                 solo_i2c_stop(solo_dev);
 174                 return -ENXIO;
 175         }
 176
 177         switch (solo_dev->i2c_state) {
 178         case IIC_STATE_START:
 179                 if (solo_dev->i2c_msg->flags & I2C_M_RD) {
 180                         solo_dev->i2c_state = IIC_STATE_READ;
 181                         ret = solo_i2c_handle_read(solo_dev);
 182                         break;
 183                 }
 184
 185                 solo_dev->i2c_state = IIC_STATE_WRITE;
 186                 /* fall through */
 187         case IIC_STATE_WRITE:
 188                 ret = solo_i2c_handle_write(solo_dev);
 189                 break;
 190
 191         case IIC_STATE_READ:
 192                 solo_dev->i2c_msg->buf[solo_dev->i2c_msg_ptr] =
 193                         solo_reg_read(solo_dev, SOLO_IIC_RXD);
 194                 solo_dev->i2c_msg_ptr++;
 195
 196                 ret = solo_i2c_handle_read(solo_dev);
 197                 break;
 198
 199         default:
 200                 solo_i2c_stop(solo_dev);
 201         }
 202
 203         return ret;
 204 }
 205
 206 static int solo_i2c_master_xfer(struct i2c_adapter *adap,
 207                                 struct i2c_msg msgs[], int num)
 208 {
 209         struct solo_dev *solo_dev = adap->algo_data;
 210         unsigned long timeout;
 211         int ret;
 212         int i;
 213         DEFINE_WAIT(wait);
 214
 215         for (i = 0; i < SOLO_I2C_ADAPTERS; i++) {
 216                 if (&solo_dev->i2c_adap[i] == adap)
 217                         break;
 218         }
 219
 220         if (i == SOLO_I2C_ADAPTERS)
 221                 return num; /* XXX Right return value for failure? */
 222
 223         mutex_lock(&solo_dev->i2c_mutex);
 224         solo_dev->i2c_id = i;
 225         solo_dev->i2c_msg = msgs;
 226         solo_dev->i2c_msg_num = num;
 227         solo_dev->i2c_msg_ptr = 0;
 228
 229         solo_reg_write(solo_dev, SOLO_IIC_CTRL, 0);
 230         solo_irq_on(solo_dev, SOLO_IRQ_IIC);
 231         solo_i2c_start(solo_dev);
 232
 233         timeout = HZ / 2;
 234
 235         for (;;) {
 236                 prepare_to_wait(&solo_dev->i2c_wait, &wait,
 237                                 TASK_INTERRUPTIBLE);
 238
 239                 if (solo_dev->i2c_state == IIC_STATE_STOP)
 240                         break;
 241
 242                 timeout = schedule_timeout(timeout);
 243                 if (!timeout)
 244                         break;
 245
 246                 if (signal_pending(current))
 247                         break;
 248         }
 249
 250         finish_wait(&solo_dev->i2c_wait, &wait);
 251         ret = num - solo_dev->i2c_msg_num;
 252         solo_dev->i2c_state = IIC_STATE_IDLE;
 253         solo_dev->i2c_id = -1;
 254
 255         mutex_unlock(&solo_dev->i2c_mutex);
 256
 257         return ret;
 258 }
 259
 260 static u32 solo_i2c_functionality(struct i2c_adapter *adap)
 261 {
 262         return I2C_FUNC_I2C;
 263 }
 264
 265 static const struct i2c_algorithm solo_i2c_algo = {
 266         .master_xfer    = solo_i2c_master_xfer,
 267         .functionality  = solo_i2c_functionality,
 268 };
 269
 270 int solo_i2c_init(struct solo_dev *solo_dev)
 271 {
 272         int i;
 273         int ret;
 274
 275         solo_reg_write(solo_dev, SOLO_IIC_CFG,
 276                        SOLO_IIC_PRESCALE(8) | SOLO_IIC_ENABLE);
 277
 278         solo_dev->i2c_id = -1;
 279         solo_dev->i2c_state = IIC_STATE_IDLE;
 280         init_waitqueue_head(&solo_dev->i2c_wait);
 281         mutex_init(&solo_dev->i2c_mutex);
 282
 283         for (i = 0; i < SOLO_I2C_ADAPTERS; i++) {
 284                 struct i2c_adapter *adap = &solo_dev->i2c_adap[i];
 285
 286                 snprintf(adap->name, I2C_NAME_SIZE, "%s I2C %d",
 287                          SOLO6X10_NAME, i);
 288                 adap->algo = &solo_i2c_algo;
 289                 adap->algo_data = solo_dev;
 290                 adap->retries = 1;
 291                 adap->dev.parent = &solo_dev->pdev->dev;
 292
 293                 ret = i2c_add_adapter(adap);
 294                 if (ret) {
 295                         adap->algo_data = NULL;
 296                         break;
 297                 }
 298         }
 299
 300         if (ret) {
 301                 for (i = 0; i < SOLO_I2C_ADAPTERS; i++) {
 302                         if (!solo_dev->i2c_adap[i].algo_data)
 303                                 break;
 304                         i2c_del_adapter(&solo_dev->i2c_adap[i]);
 305                         solo_dev->i2c_adap[i].algo_data = NULL;
 306                 }
 307                 return ret;
 308         }
 309
 310         return 0;
 311 }
 312
 313 void solo_i2c_exit(struct solo_dev *solo_dev)
 314 {
 315         int i;
 316
 317         for (i = 0; i < SOLO_I2C_ADAPTERS; i++) {
 318                 if (!solo_dev->i2c_adap[i].algo_data)
 319                         continue;
 320                 i2c_del_adapter(&solo_dev->i2c_adap[i]);
 321                 solo_dev->i2c_adap[i].algo_data = NULL;
 322         }
 323 }